Accurate thickness mapping of large structures is critical to assess the residual life of structures subject to erosion or corrosion damage. Conventional gauging devices require a handheld sensor to scan across a region of interest of a structure. Conventional gauging devices are limited to assess regions of interest that are easily accessible to be scanned. Conventional gauging devices are not suitable for regions of interest that are difficult to access for scanning or require continuous monitoring.
Another conventional thickness mapping approach includes guided wave tomography (GWT). Conventional GWT transmits waves through the region of interest. The signals resulting from the propagated waves are processed to generate a representation of the wall thickness distribution for the region of interest. Conventional GWT implements a conventional straight ray model to generate the representation based on the assumption that the waves travel on straight paths. The conventional straight ray model fails to accurately describe ultrasonic waves that propagate through structures with non-uniform thickness, such as corroded pipes, thus resulting in poor estimations of wall thickness loss for the structures.